CVE-2023-41378

Calico Typha hangs during unclean TLS handshake

HIGH
7.5
CVSS Score
Published: November 6, 2023 at 03:00 PM UTC
Updated: June 17, 2026 at 06:22 AM UTC
5 products affected across 2 vendorsCalico EnterpriseCalico CloudCalico OS

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Severity
HIGH7.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

Description

In certain conditions for Calico Typha (v3.26.2, v3.25.1 and below), and Calico Enterprise Typha (v3.17.1, v3.16.3, v3.15.3 and below), a client TLS handshake can block the Calico Typha server indefinitely, resulting in denial of service. The TLS Handshake() call is performed inside the main server handle for loop without any timeout allowing an unclean TLS handshake to block the main loop indefinitely while other connections will be idle waiting for that handshake to finish.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 18.0.0
Affected range stops below 18.0.0, so it looks safe — our inference, not a vendor statement
v < 3.15.43.16.0 ≤ v < 3.16.43.17.0 ≤ v < 3.17.2
Affected range stops below 3.15.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.16.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.17.2, so it looks safe — our inference, not a vendor statement
v < 3.25.23.26.0 ≤ v < 3.26.3
Affected range stops below 3.25.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.26.3, so it looks safe — our inference, not a vendor statement
v ≤ v3.15.3v3.16.0 ≤ v ≤ v3.16.3v3.17.0 ≤ v ≤ v3.17.13.16.03.17.0
v ≤ v3.25.1v3.26.0 ≤ v ≤ v3.26.23.26.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHTigera
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400CWE-703CWE-755

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